Isn't XMPP the base of all major chat services?
I used my own client (Psi+) for a while with Facebook chat but since I no longer use Facebook I don't know if that still works. Too bad none of them support federation any longer.
Google Talk/Hangouts still uses XMPP and I use that right now.
At least 8 banks in my city use XMPP for internal chats since 2005 at least. Cisco has an xmpp product. Oracle uses xmpp for internal chat communications (i know it because their employees contacted us many times, and we slightly modified our xmpp client so that could connect to it without problems). Fortnite, eve online based their chats on xmpp, WhatsApp runs on a modified XMPP. Quite enough serious organisations, no?
It feels to me that the author would complain about the internet because we already have ordinary mail. Just a tantrum.